[handbook] Fix path of example and add hint to website guide

See merge request !2666

[handbook] Fix and update installation instructions

See merge request !2664

In particular remove non-recommended installation command that also
contained an outdated --use-cmake option which doesn't exist anymore.

[test][pnm] Fix test label

See merge request !2662

[test] Increase timeout of tests that take long without compiler optimisations

See merge request !2661

For the test coverage report the test suite has to be run in debug mode to get useful line annotations.

[test] Increase timeout of tests that take long without compiler optimisations

See merge request !2660

For the test coverage report the test suite has to be run in debug mode to
get useful line annotations.

[ci] make pipeline search more robust

See merge request !2659

the CI enters the repo in a detached HEAD state, and thus, the query if
a pipeline was run on the same branch failed. We now check the last
commits.

[ci] fix target tree argument

See merge request !2657

[ci] Use api read token for read access

See merge request !2655

Feature/continuous master pipeline status

See merge request !2644

The commands (e.g. pipeline queries via API) may contain sensible
information that we don't want to display e.g. in the output of jobs
from the GitLab CI

Resolve "Create Release Issue template"

Closes #1008

See merge request !2641

[embedded] Make source stencil lookup slightly more efficient

See merge request !2653

[install] update script versions to 3.4

See merge request !2647